1. Field of the Invention
This invention relates to radiography apparatus and an associated method and, more specifically, it relates to an efficient system for noninvasively visualizing moving portions of an object by employing substantially parallel beams of radiation and subtraction techniques.
2. Description of the Prior Art
The advantageous use of radiation, such as x-rays, gamma rays and nuclear particles has long been known in medical, industrial and other environments. A wide variety of systems and procedures have been employed in such uses depending, in part, upon safety considerations, the nature of the object to be imaged and equipment limitations. See generally U.S. Pat. Nos. 3,767,931; 3,829,701; 3,866,047; 3,934,151; 3,947,689 and 3,973,127.
It has also been known to use various forms of photodetectors, such as photomultipliers, in such systems. See generally U.S. Pat. Nos. 4,010,371 and 4,029,964. It has also been known to employ self-scanning photodiode arrays for spectroscopy (Snow, Research-Development, April 1976) and for medical and nonmedical uses (See our U.S. Pat. No. 4,179,100, the disclosure of which is hereby expressly incorporated herein by reference).
It has also been known to provide systems wherein collimated radiation is permitted to pass through an object and impinge upon a scintillator screen with fiber optic coupling means transporting the light to one or more arrays of self-scanning photodiodes which emit a responsive electrical signal which may then be computer enhanced or otherwise processed or imaged See U.S. Pat. No. 4,179,100.
In spite of these prior disclosures, there is needed an effective means for low dosage, clear visualization of coronary arteries and other portions of the body as well as other objects with high resolution, while eliminating undesired obstruction to full visualization, particularly with respect to moving sections which are desired to be visualized.